The invention relates to a radar apparatus comprising antenna means, transmitter means connected to the antenna means, for generating and transmitting pulses, receiver means connected to the antenna means, for the reception, per transmitted pulse, of a radar echo signal, a video processor connected to the receiver means, comprising a slow moving target detection unit provided with a coherent clutter map divided into range-azimuth cells.
What are meant by slow moving targets are targets with radial speeds so low that they are not, on the basis of their speeds, discernable from clutter. What is meant by a coherent clutter map is a clutter map in which clutter information is stored as complex values, representing complex clutter strengths.
Such an apparatus is known from the report "Low Doppler target detection in ground clutter" by J. S. Bird, November 1985, Communications Research Centre, Ottawa, Canada. According to this report, a coherent clutter map will only serve a useful purpose when used in a non-moving antenna, such as a step-scan phased array antenna.